View source for WBR1067

 {{WBRQuestion
|QuestionAuthor= {{MM}}
|ExamType=USMLE Step 3
|MainCategory=Emergency Room
|SubCategory=Electrolytes
|MainCategory=Emergency Room
|SubCategory=Electrolytes
|MainCategory=Emergency Room
|SubCategory=Electrolytes
|MainCategory=Emergency Room
|MainCategory=Emergency Room
|SubCategory=Electrolytes
|MainCategory=Emergency Room
|SubCategory=Electrolytes
|MainCategory=Emergency Room
|SubCategory=Electrolytes
|MainCategory=Emergency Room
|SubCategory=Electrolytes
|MainCategory=Emergency Room
|MainCategory=Emergency Room
|SubCategory=Electrolytes
|Prompt=A 67 year-old male brought to Emergency department by his son after he became disoriented and confused.  His son mentioned that he is living alone, ¬¬and he was okay at his last visit 2 days ago, and he showed some seizures while on the way.  The patient has a past medical history of alcoholic liver cirrhosis.  On examination, the patient is confused, disoriented to time and place.   His blood pressure is  90/60 mmHg, pulse 120 beat per minute, respiration 23/m, and temperature 37 C.   Cardiopulmonary exam was unremarkable.  Abdominal exam shows tense ascites and a shrunken liver.  Lower extremities had 3+ pitting edema.  His laboratory tests are shown below.  
•	Sodium  	110  (N: 135-146 mmol/L)
•	Potassium       3.8   (N: 3.5-5.3 mmol/L)
•	Glucose  	100  (N: 70-110 mg/dl)
•	Chloride  	98    (N: 98-108 mmol/L)	
•	Total CO2   	25    (N: 23-27 mmol/L)
Which of the following is the best next step in managing his hyponatremia?

|Explanation=The decrease in effective circulating arterial volume due to this patient`s liver disease is responsible for ADH secretion in this patient.  Hyponatremia is defined as plasma sodium concentration less than 135 mEq/L.  Most patients with hyponatremia are asymptomatic.  Symptoms do not usually appear until the plasma sodium level drops below 120 mEq per L.  Hyponatremia can be developed in cases of excess water intake that exceed the excretory capacity of the kidneys.  Other causes include impared renal functions and ability to excrete excess water, or inappropriate secretion of ADH.   Acute severe hyponatremia (i.e., less than 125 mmol per L) usually is associated with neurologic symptoms and should be treated urgently because of the high risk of cerebral edema and hyponatremic encephalopathy.   Treat with 3% NaCl to begin with (100 ml infused over 10 minutes and repeated once if needed).  Transition to 0.9% NaCl/vaptans at sodium levels > 125 mEq/L.
|AnswerA=Hypotonic saline infusion
|AnswerAExp=Incorrect
Hypotonic saline infusion will increase the hyponatremia degree and worsen the case.  

|AnswerB=Isotonic saline infusion
|AnswerBExp=Incorrect
Isotonic saline infusion is not used in acute cases who need rapid correction of the hyponatremia to prevent the occurance of cerebral edema.  Instead 3% NaCl is used, then transition to 0.9% NaCl/vaptans at sodium levels > 125 mEq/L.

|AnswerC=Hypertonic saline infusion
|AnswerCExp=Correct
Acute severe hyponatremia treated with 3% NaCl, then Transition to 0.9% NaCl/vaptans at sodium levels > 125 mEq/L.

|AnswerD=Water restriction
|AnswerDExp=Incorrect
Water restriction is used wen the case is mild asymptomatic.

|AnswerE=Intravenous diuretics
|AnswerEExp=Incorrect
Diuretics are not indicated in the treatment of hyponatremia. 

|EducationalObjectives=Acute severe hyponatremia (i.e., less than 125 mmol per L) usually is associated with neurologic symptoms and should be treated with 3% NaCl to begin with (100 ml infused over 10 minutes and repeated once if needed).  Transition to 0.9% NaCl/vaptans at sodium levels > 125 mEq/L.
|References=http://www.wikidoc.org/index.php/Hyponatremia_resident_survival_guide
|RightAnswer=C
|WBRKeyword=[[Hyponatremia]]
|Approved=No
}}